AQ1056

Buffer 10 Standard

$7.49 – $13.99

Buffer solution lets you calibrate any pH tester to ensure accuracy. Choose from pH 4, 7 or 10.

Solution helps you achieve the accuracy that's critical for measuring pH in wastewater, storm water and process liquids
Makes calibration easy - just adjust your tester to the pH measurement of the solution in a clean container
Choose from pH 4, 7 or 10 solution
If unopened, shelf life is 2 years; once opened, use pH 4 and pH 7 within 90 days, pH 10 within 30 days

Packing:

$7.49

pH Calibration Challenge

To calibrate pH measuring systems you must use a solution with a known pH value, also known as pH reference or buffer pH solution. The accuracy of your subsequent pH measurements is dependent on how accurately the pH measuring system is calibrated, so particular attention must be paid to this step. Because there are a great number of different buffer pH solutions available many people are uncertain about how many and what pH calibration solutions should be used.

What is a buffer pH solution and how many pH calibration points are reasonable?

A buffer pH solution is composed of either a weak acid and its conjugated base or a weak base and its conjugated acid. The main characteristic of a buffer pH calibration solution is that the pH value of the solution will not alter when a small amount of acid or base is added. The components and their concentration can cause the pH value to vary across a wide range (e.g. HCl + sodium citrate 1–5, citric acid + sodium citrate 2.5–5.6, acetic acid + sodium acetate 3.7–5.6, Na₂HPO₄ + NaH₂HPO₄ 6–9, borax + sodium hydroxide 9.2–11).

The pH value of a calibration solution also changes with temperature. Below is the temperature behavior of reference pH buffers.

Temperature (°C)	pH 4	pH 7	pH 10
10	3.997	6.923	9.332
20	4.001	6.881	9.225
25	4.005	6.865	9.180
40	4.027	6.838	9.068
50	4.050	6.833	9.011

Unlike reference pH calibration solutions, the composition of technical buffer pH solutions is not regulated. Therefore, the temperature behavior can vary even when they show the same nominal pH at 25°C. At calibration temperatures other than 25°C, considerable errors may occur. The calibration procedure also influences accuracy.

One-point Calibration

A one-point calibration uses a single reference pH buffer solution. It verifies the zero point of the electrode and assumes linear behavior. Fast but less accurate.

Two-point Calibration

This uses two buffer pH solutions at least two pH units apart. It determines the zero point and the slope. This is the most commonly used accurate calibration.

Multipoint Calibration

Uses three or more buffer solutions (difference ≥ 0.5 pH). Accuracy is higher, especially when using pH 4, 7, and 10. Regression or segment method calculates the curve. Check R² (should be approx. 1).

Three-point calibration with Dawn buffer pH calibration solutions 4, 7, and 10 increases accuracy for most pH measurements.

Disclaimer: Any of the above statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent disease. This information is general and should not be considered medical advice. This product is for research use only. Test before use. Discontinue immediately if adverse reactions occur.